1. Technical Field
The present invention relates generally to mobile communication systems and, more particularly, to general packet radio services for delivering data over a circuit switched telephone network.
2. Description of the Related Art
A General Packet Radio Service (GPRS) is a non-voice value added service that allows information to be sent and received across a mobile telephone network. It supplements, or rides on top, of today's circuit switched data and short message service W networks. The theoretical maximum speed of GPRS includes speeds of up to approximately 171.2 kilobits per second (kbps). This maximum speed is achievable in GPRS systems using all eight timeslots at the same time in a Time Division Multiple Access (TDMA) context.
This speed is about three times as fast as data transmission speeds possible over today's fixed telecommunication networks and ten times as fast as current circuit switched data services on Global System for Mobile Communications (GSM) standard TDMA networks. Thus, GPRS systems are advantageous in that they require less system resources to transmit a fixed amount of data in comparison to using a traditional circuit switched approach. By allowing information to be transmitted more quickly, immediately, and efficiently, across the mobile network, GPRS may well be a relatively less costly mobile data service compared to Short Message Service (SMS) and circuit switched data services.
GPRS also facilitates instant connections in which information can be sent or received immediately as the need arises, subject to radio coverage. No dial up modem connection is necessary. GPRS, similar to some broadband connections for personal computers, often is referred to as being “always connected”. Thus, another one of the advantages of GPRS is that data may be transmitted immediately, whenever the need arises. In contrast to circuit switched data networks in which a connection must be established to transmit a data packet or data file, GPRS operation is extremely efficient in those situations in which a small amount of data is to be sent. As the emphasis of many designs today are to create wireless computer networks, and to connect data devices including personal computers to wireless transceivers and mobile terminals, such a system that provides instantaneous response is very important for time critical applications, and, more generally, for the implementation of wireless computer networks. For example, a remote credit card authorization system implemented in a wireless network can be greatly improved if it is unnecessary for the customer to wait the amount of time that is required to establish a connection. Additionally, GPRS facilitates the use of Internet applications not only from personal computers, but also from appliances and machines. It is anticipated that appliances will be designed to be coupled to the Internet to facilitate control either onsite or remotely. While some people envision connecting these appliances to a network port by physical lines, it would clearly be advantageous to be able to connect such appliances to the Internet through a wireless link. GPRS will facilitate the creation of Internet controlled appliance networks through a wireless medium.
As suggested before, GPRS involves overlaying a packet based air interface on an existing circuit switched wireless network. For example, the circuit switched wireless network may comprise a GSM network. Accordingly, the user is given an option to utilize a packet based data service. In order to overlay a packet based air interface over a circuit switched network, the GPRS standard defines new infrastructure nodes to minimize the impact to existing networks in terms of hardware and software.
One advantage of GPRS is that the packet switching that results from the infrastructure nodes allows the use of GPRS radio resources only when users actually are sending or receiving data. Unlike traditional circuit switched voice networks, a connection is not continuously reserved for a user for the intermittent transmission of data. This efficient use of scarce radio resources means that larger number of GPRS users can share the same bandwidth and be served from a single base station or cell. The actual number of users, of course, that may use the system at one time depends on the amount of data being transferred.
Another delivery network, namely, the Universal Mobile Telecommunications System (UMTS) network, also provides connectionless services. Moreover, GPRS and UMTS support push services. A push service is the delivery of data or multimedia information from a network node to user equipment for the purpose of activating the user equipment or for providing information from the network. A push service also can include activating a Packet Data Protocol (PDP) context, if necessary. Examples of delivery networks that offer push services include, as stated, the GPRS network, but can also include other equipment, such as a session initiation protocol (SIP) proxy, a push proxy or an SMS service center. Push services are expected to be popular because of their ability to deliver advertisements, as well as subscriber ordered upon notice such as traffic conditions, sports scores, stock quotes, etc. New services and features being contemplated require that push capabilities be implemented to enable external Internet protocol networks to deliver data to third generation wireless terminals in the paging system (PS) domain.
Packet domain utilized in GPRS and UMTS system uses a packet-mode technique to transfer high speed and low speed data and signaling in an efficient manner and generally optimizes network and radio resources. Strict separation between the radio subsystems and network subsystems is maintained thereby allowing a network subsystem to be reused with other radio technologies. A common packet domain core network is used for both GSM and UMTS. The common core network provides packet switch services and supports differing quality of service levels to allow efficient transfer of non-continuous bit rate traffic (for example, bursty data transfers).
Some specifications allow operators to provide push services by using static IP addresses or by having long lasting PDP context. However, it would be advantageous to also provide push services within systems that utilize dynamic IP addressing schemes. In other words, push services should be provided to any mobile terminal regardless of whether it has a static or dynamic IP address. In order to use dynamic IP addresses, it is necessary for the network to be able to initiate a PDP context for a mobile subscriber.
In GPRS and UMTS networks, however, a network-initiated PDP context activation is not practical unless a static IP address is allocated for the subscriber in some current systems. The use of static IP address assignments is cumbersome, however, because it wastes available address space for mobile subscribers that are inactive. Thus, it is desirable to initiate PDP context activation with dynamic address assignments. The use of dynamic assignment schemes means that a user's address is not predictable and known to all other systems. Accordingly, specific problems arise when a user wishes to establish a connection with another device without knowing the address of that device. Accordingly, systems are required so that the dynamic address of a terminating device may be ascertained for the creation of a connection or session.
The Access Point Name (APN) is a reference to a specific GGSN that is to be used. Additionally, the access point name may be used to identify the external network and even a service that is to be offered. The access point name typically comprises two portions. A first portion carries the APN network identifier that serves as a label. This APN network identifier is a fully qualified domain name according to DNS naming conventions. In order to guaranty the uniqueness of the APN, the packet domain PLMN allocates, to an ISP or corporation, an APN network identifier identical to their domain name in the public Internet. A second portion of the access point name is the APN operator identifier that is used optionally. It, too, is a fully qualified domain name according to DNS naming conventions.
The APN is an APN network identifier for the selected APN in the Activate PDP Context Request message. The GGSN uses the APN to find an external network and, optionally, to activate a service for the APN. In some embodiment of the invention, the original Activate PDP Context Request message further includes a selection mode which indicates whether a subscribed APN was selected or a non-subscribed APN was selected.
One specific problem is that there is an ever-present need to develop systems whose growth is relatively transparent and painless. Stated differently, there is a large emphasis to develop scaleable networks that may be easily modified to accommodate changes and additions to the network. As designs evolve to create scaleable networks, however, unique challenges exist for inter-network communications that are designed to be scaleable. For example, a first network may attempt to gain access to a second network through a first gateway device to create a connection or data session while the second network, for its own reasons, tends to select a second or different gateway for the connection or data session. In such a case, a conflict exists between the two networks and synchronizing the gateway point of entry and exit for each of the two networks becomes a problem that must be solved.
There is a need, therefore, for a system and method that supports and provides scalability while also enabling separate networks to synchronize the entry and exit gateways so that connections and data sessions may be established.